The long fixation on race, gender, age and class in the Democratic primaries will soon spread to the general election as the Democratic nominee seeks the keys to the Republican kingdom: Ohio and Florida.

Both states were hotly contested battlegrounds in 2000 and 2004 that gave George W. Bush two terms in the White House. Without them, Republicans lose the presidency.

If Sen. John McCain holds both states for Republicans in November, Democrats must put together 47 offsetting votes in the state-based, winner-take-all Electoral College.

Ohio and Florida are the foundation of Sen. Hillary Rodham Clinton's last-ditch attempt to convince fellow Democrats that her strengths with Latinos, women, seniors and the white working class play best against McCain in roughly 10 swing states.

Sen. Barack Obama's victories in nearly every primary since February have rested on African Americans, upscale whites and young people. He has consistently performed poorly among key populations in Florida - Latinos, seniors and Jewish voters - and in Ohio among older women, Catholics and the white working class, what some call the "blue-collar, blue-hair vote."

It was perhaps inevitable that the history-making Democratic candidates would open a race and gender divide by stirring intense group loyalty. But now conservative Democrats are worried.

Sixteen members of Congress from Pennsylvania, Tennessee, Ohio, Missouri, Florida, Nevada and other swing states wrote in a letter posted on Clinton's Web site Friday that her Pennsylvania victory last month was a "wake-up call."

"Hillary has racked up victories in bellwether states like Ohio, Pennsylvania and now Indiana that are absolutely vital to winning the White House and maintaining our Congressional majority in the fall," they wrote.

Must-have voters

"Some demographics are have-to-have, not nice-to-have," said Rep. Ellen Tauscher, a Clinton superdelegate representing Walnut Creek, who did not sign the letter.

Some conservative House Democrats privately worry that having Obama at the top of their ticket could damage their own re-election chances.

Obama supporters dismiss Clinton's strength among parts of the Democratic base as a specious extrapolation of primary results. Primaries have nothing to do with a matchup against McCain, they contend.

There is certainly danger in such analogies. Clinton earlier said that winning big states such as California made her the better candidate in November. Obama is just as likely to win solidly Democratic California.

Republican primaries likewise have little to do with general-election prospects. McCain won the New York GOP primary, but has little chance there against a Democrat. He lost Deep South states to Republican rival former Arkansas Gov. Mike Huckabee in the primaries, but will probably win them in the fall. Experts similarly dismiss Obama's claims that he can put Southern states in play based on his primary victories.

"Reading into what happened in a primary is acceptable, but predicting from that what is going to happen in the future is not," said Gerald Austin, a longtime Ohio political strategist. Older, white female Democrats will be deciding between Obama and McCain, not Obama and Clinton.

A McCain-Obama contest in Ohio, Austin said, "is going to be close."

McCain will have to battle a bad economy. Obama will hope that the youth vote will offset white racism.

Austin said he has not seen such enthusiasm among young voters since 1968. "If he keeps those young people and adds to them, I think that that makes up for anything he may lose because there are people in states like Ohio who will not vote for anybody who's African American, ever."

In Florida, Clinton is indisputably stronger against McCain, whose campaign would alter its Florida strategy were she the nominee.

A McCain operative said Obama is much weaker among the Florida voting blocs that McCain is targeting, including retirees, veterans and Republican-leaning Cubans. McCain can also count on help from Republican Gov. Charlie Crist. Experts predict Obama would lose Florida.

"There is no way a Democrat can win in November if you're not able to bring together not only African Americans but blue-collar workers, Catholics, women, the base vote that has gone to Hillary," Panetta said. "If those divisions remain, Democrats are not going to win in November. It's that simple."

Others said Obama's youth vote changes the old Democratic formula.

"The fallacy there is that Barack Obama has drastically expanded the potential Democratic base in a general election," said California Democratic consultant Garry South.

South also sees an enormous money advantage. "You're looking at what is probably going to be the most dire resource differential Democrats have ever had going in their favor," South said. McCain will take $84 million in public financing, while Obama, South predicts, could raise as much as $300 million.

In the end, the wild card may be independent voters.

True independents, excluding weakly affiliated partisans, make up about 15 percent of the electorate. They swing elections.

"They're the ones who tend to respond to the big issues in the end - war, peace, the economy, the incumbent president," Sabato said. "They may also be susceptible to other factors, including race. ...This is an unprecedented election. We have never had an African American on the ballot for president in a general election."

Appeal to independents

Both McCain and Obama enjoy a strong affinity with independents and will try to cast their rival as a common partisan - Obama as a classic elitist liberal, and McCain as a tired replay of President Bush.

The Obama campaign believes it can redraw the electoral map by attracting independents in a way the more polarizing Clinton never could. Virginia, a former GOP stronghold where Obama had a runaway victory, will be a case study. McCain hopes to hold the state by appealing to GOP moderates and drawing from the big naval base in Norfolk.

Obama hopes for a major breakthrough in the West with Nevada, Colorado and New Mexico all drifting Democratic. McCain believes his strength in his home state of Arizona will block those incursions.

The Latino vote faded from the spotlight after the California and Texas primaries, but will re-emerge in the battle for the Southwest. Obama has struggled with Hispanics, while McCain won some loyalty after championing a path to legalization for illegal immigrants.

McCain will target the states lining the upper Mississippi River: Missouri, Iowa and Wisconsin. He believes he can nab Pennsylvania, New Hampshire and Maine from Democrats. McCain revived his moribund candidacy last summer by blanketing New Hampshire with town-hall meetings.

"The biggest difference between 2004 and 2008 is the number of states that are in play," said a McCain strategist who was not allowed to speak for attribution.

Gender may be a fault line today, but if it's a 71-year-old Republican running against a 46-year-old Democrat, age could become the new demographic frontier.

"We haven't seen anything like this, ever," Austin said. "We're going to have the first African American ever to run as the nominee of either party against the oldest person ever to run for president. We can make assumptions based upon conventional wisdom, and after you make them, you throw them out the window. Because if conventional wisdom would have served this year, it would be Hillary Clinton versus Rudy Giuliani."

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